In a square baler, a plunger reciprocates within a bale case to compress slices of crop that are fed into a baling chamber through an opening in the floor of the bale case. After a bale has achieved a desired length, it is tied with twines that are knotted by an array of knotters mounted above the bale case. Pivoted arcuate needles pass through the baling chamber to bring twines from beneath the baling chamber up to the level of the knotters for tying around the completed bales.
To enable twines to be wrapped around the completed bales, at least the floor of the baling chamber is not made as a single continuous surface and is instead made up of separate spaced elongate members, herein termed profiles, the gaps between which allowing the twines and the needles to pass into the baling chamber. A similar construction using spaced profiles may also be used for the side walls and for the top wall of the baling chamber.
To allow the density of the bale to be modified, the top wall is often designed to be movable, this being achieved by including in the top wall a door that can pivot relative to the side walls of the baling chamber about a horizontal axis.
In order to maintain the integrity of the bale case, a support structure is required to hold the profiles in their desired relative positions and to prevent deformation of the bale case. A typical construction of a known bale case is shown in FIG. 1, which is a perspective view of a conventional bale case as seen from the rear end of the baler.
In FIG. 1, the floor 12 of the bale case 10 is formed of spaced profiles 13 that are secured at their rear end to a first frame 14 and at their front end to a second frame, which is termed the density belt 16. The rear frame 14 and the density belt 16 are each conventionally formed of rigid beams that are welded to one another at the corners. The two frames 14, 16 are connected to one another by longitudinally extending beams 18 and 20 to form a space frame on which side walls and a pivoted ceiling door (not shown) are mounted to define a rectangular or square baling chamber.
The top beam 16a of the density belt 16 serves several functions. First, it prevents the two upright beams 16b of the density belt 16 from splaying apart and for this it has withstand the compression forces applied to the crop by the reciprocating plunger. Second, the top beam 16a prevents the top wall of the baling chamber from bowing outwards. Third, the beam 16a provides a secure location for the pivot of the movable top door of the baling chamber.
The knotters also need to be securely mounted in relation to the bale case 10 and conventionally they are mounted on a separate beam located forward of the density belt 16. The top beam 16a of the density belt 16 in this case is required not to interfere with the removal of debris from the vicinity of the knotters.
Further, U.S. Pat. No. 5,735,199 shows a baler having a baling chamber formed by a pair of elongated top rails, bottom rails, side rails and a squeeze mechanism positioned proximate the discharge end of the bale chamber for symmetrically adjusting the cross-section size of the discharge opening. The squeeze mechanism includes a vertical squeeze assembly for adjusting the vertical distance between the top and bottom rails, and a horizontal squeeze assembly for adjusting the horizontal distance between the left and right side rails. Each squeeze assembly includes a jaw-type lever assembly surrounding its respective rails and a cylinder assembly that selectively shift its lever assembly and its respective rails towards and away from one another.
In U.S. Pat. No. 2,724,324 an automatic tension device for balers is shown, where the tension device is used to adjust the tension in the baling chamber to compensate for varying hay conditions such that the bales may be maintained a reasonable constant weight.